// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
// 3. Neither the name of the copyright holders nor the names of its
//    contributors may be used to endorse or promote products derived from
//    this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
// THE POSSIBILITY OF SUCH DAMAGE.
package org.springframework.asm;

/**
 * A dynamically extensible vector of bytes. This class is roughly equivalent to a DataOutputStream
 * on top of a ByteArrayOutputStream, but is more efficient.
 *
 * @author Eric Bruneton
 */
public class ByteVector {

	/**
	 * The content of this vector. Only the first {@link #length} bytes contain real data.
	 */
	byte[] data;

	/**
	 * The actual number of bytes in this vector.
	 */
	int length;

	/**
	 * Constructs a new {@link ByteVector} with a default initial capacity.
	 */
	public ByteVector() {
		data = new byte[64];
	}

	/**
	 * Constructs a new {@link ByteVector} with the given initial capacity.
	 *
	 * @param initialCapacity the initial capacity of the byte vector to be constructed.
	 */
	public ByteVector(final int initialCapacity) {
		data = new byte[initialCapacity];
	}

	/**
	 * Constructs a new {@link ByteVector} from the given initial data.
	 *
	 * @param data the initial data of the new byte vector.
	 */
	ByteVector(final byte[] data) {
		this.data = data;
		this.length = data.length;
	}

	/**
	 * Puts a byte into this byte vector. The byte vector is automatically enlarged if necessary.
	 *
	 * @param byteValue a byte.
	 * @return this byte vector.
	 */
	public ByteVector putByte(final int byteValue) {
		int currentLength = length;
		if (currentLength + 1 > data.length) {
			enlarge(1);
		}
		data[currentLength++] = (byte) byteValue;
		length = currentLength;
		return this;
	}

	/**
	 * Puts two bytes into this byte vector. The byte vector is automatically enlarged if necessary.
	 *
	 * @param byteValue1 a byte.
	 * @param byteValue2 another byte.
	 * @return this byte vector.
	 */
	final ByteVector put11(final int byteValue1, final int byteValue2) {
		int currentLength = length;
		if (currentLength + 2 > data.length) {
			enlarge(2);
		}
		byte[] currentData = data;
		currentData[currentLength++] = (byte) byteValue1;
		currentData[currentLength++] = (byte) byteValue2;
		length = currentLength;
		return this;
	}

	/**
	 * Puts a short into this byte vector. The byte vector is automatically enlarged if necessary.
	 *
	 * @param shortValue a short.
	 * @return this byte vector.
	 */
	public ByteVector putShort(final int shortValue) {
		int currentLength = length;
		if (currentLength + 2 > data.length) {
			enlarge(2);
		}
		byte[] currentData = data;
		currentData[currentLength++] = (byte) (shortValue >>> 8);
		currentData[currentLength++] = (byte) shortValue;
		length = currentLength;
		return this;
	}

	/**
	 * Puts a byte and a short into this byte vector. The byte vector is automatically enlarged if
	 * necessary.
	 *
	 * @param byteValue  a byte.
	 * @param shortValue a short.
	 * @return this byte vector.
	 */
	final ByteVector put12(final int byteValue, final int shortValue) {
		int currentLength = length;
		if (currentLength + 3 > data.length) {
			enlarge(3);
		}
		byte[] currentData = data;
		currentData[currentLength++] = (byte) byteValue;
		currentData[currentLength++] = (byte) (shortValue >>> 8);
		currentData[currentLength++] = (byte) shortValue;
		length = currentLength;
		return this;
	}

	/**
	 * Puts two bytes and a short into this byte vector. The byte vector is automatically enlarged if
	 * necessary.
	 *
	 * @param byteValue1 a byte.
	 * @param byteValue2 another byte.
	 * @param shortValue a short.
	 * @return this byte vector.
	 */
	final ByteVector put112(final int byteValue1, final int byteValue2, final int shortValue) {
		int currentLength = length;
		if (currentLength + 4 > data.length) {
			enlarge(4);
		}
		byte[] currentData = data;
		currentData[currentLength++] = (byte) byteValue1;
		currentData[currentLength++] = (byte) byteValue2;
		currentData[currentLength++] = (byte) (shortValue >>> 8);
		currentData[currentLength++] = (byte) shortValue;
		length = currentLength;
		return this;
	}

	/**
	 * Puts an int into this byte vector. The byte vector is automatically enlarged if necessary.
	 *
	 * @param intValue an int.
	 * @return this byte vector.
	 */
	public ByteVector putInt(final int intValue) {
		int currentLength = length;
		if (currentLength + 4 > data.length) {
			enlarge(4);
		}
		byte[] currentData = data;
		currentData[currentLength++] = (byte) (intValue >>> 24);
		currentData[currentLength++] = (byte) (intValue >>> 16);
		currentData[currentLength++] = (byte) (intValue >>> 8);
		currentData[currentLength++] = (byte) intValue;
		length = currentLength;
		return this;
	}

	/**
	 * Puts one byte and two shorts into this byte vector. The byte vector is automatically enlarged
	 * if necessary.
	 *
	 * @param byteValue   a byte.
	 * @param shortValue1 a short.
	 * @param shortValue2 another short.
	 * @return this byte vector.
	 */
	final ByteVector put122(final int byteValue, final int shortValue1, final int shortValue2) {
		int currentLength = length;
		if (currentLength + 5 > data.length) {
			enlarge(5);
		}
		byte[] currentData = data;
		currentData[currentLength++] = (byte) byteValue;
		currentData[currentLength++] = (byte) (shortValue1 >>> 8);
		currentData[currentLength++] = (byte) shortValue1;
		currentData[currentLength++] = (byte) (shortValue2 >>> 8);
		currentData[currentLength++] = (byte) shortValue2;
		length = currentLength;
		return this;
	}

	/**
	 * Puts a long into this byte vector. The byte vector is automatically enlarged if necessary.
	 *
	 * @param longValue a long.
	 * @return this byte vector.
	 */
	public ByteVector putLong(final long longValue) {
		int currentLength = length;
		if (currentLength + 8 > data.length) {
			enlarge(8);
		}
		byte[] currentData = data;
		int intValue = (int) (longValue >>> 32);
		currentData[currentLength++] = (byte) (intValue >>> 24);
		currentData[currentLength++] = (byte) (intValue >>> 16);
		currentData[currentLength++] = (byte) (intValue >>> 8);
		currentData[currentLength++] = (byte) intValue;
		intValue = (int) longValue;
		currentData[currentLength++] = (byte) (intValue >>> 24);
		currentData[currentLength++] = (byte) (intValue >>> 16);
		currentData[currentLength++] = (byte) (intValue >>> 8);
		currentData[currentLength++] = (byte) intValue;
		length = currentLength;
		return this;
	}

	/**
	 * Puts an UTF8 string into this byte vector. The byte vector is automatically enlarged if
	 * necessary.
	 *
	 * @param stringValue a String whose UTF8 encoded length must be less than 65536.
	 * @return this byte vector.
	 */
	// DontCheck(AbbreviationAsWordInName): can't be renamed (for backward binary compatibility).
	public ByteVector putUTF8(final String stringValue) {
		int charLength = stringValue.length();
		if (charLength > 65535) {
			throw new IllegalArgumentException("UTF8 string too large");
		}
		int currentLength = length;
		if (currentLength + 2 + charLength > data.length) {
			enlarge(2 + charLength);
		}
		byte[] currentData = data;
		// Optimistic algorithm: instead of computing the byte length and then serializing the string
		// (which requires two loops), we assume the byte length is equal to char length (which is the
		// most frequent case), and we start serializing the string right away. During the
		// serialization, if we find that this assumption is wrong, we continue with the general method.
		currentData[currentLength++] = (byte) (charLength >>> 8);
		currentData[currentLength++] = (byte) charLength;
		for (int i = 0; i < charLength; ++i) {
			char charValue = stringValue.charAt(i);
			if (charValue >= '\u0001' && charValue <= '\u007F') {
				currentData[currentLength++] = (byte) charValue;
			} else {
				length = currentLength;
				return encodeUtf8(stringValue, i, 65535);
			}
		}
		length = currentLength;
		return this;
	}

	/**
	 * Puts an UTF8 string into this byte vector. The byte vector is automatically enlarged if
	 * necessary. The string length is encoded in two bytes before the encoded characters, if there is
	 * space for that (i.e. if this.length - offset - 2 &gt;= 0).
	 *
	 * @param stringValue   the String to encode.
	 * @param offset        the index of the first character to encode. The previous characters are supposed
	 *                      to have already been encoded, using only one byte per character.
	 * @param maxByteLength the maximum byte length of the encoded string, including the already
	 *                      encoded characters.
	 * @return this byte vector.
	 */
	final ByteVector encodeUtf8(final String stringValue, final int offset, final int maxByteLength) {
		int charLength = stringValue.length();
		int byteLength = offset;
		for (int i = offset; i < charLength; ++i) {
			char charValue = stringValue.charAt(i);
			if (charValue >= 0x0001 && charValue <= 0x007F) {
				byteLength++;
			} else if (charValue <= 0x07FF) {
				byteLength += 2;
			} else {
				byteLength += 3;
			}
		}
		if (byteLength > maxByteLength) {
			throw new IllegalArgumentException("UTF8 string too large");
		}
		// Compute where 'byteLength' must be stored in 'data', and store it at this location.
		int byteLengthOffset = length - offset - 2;
		if (byteLengthOffset >= 0) {
			data[byteLengthOffset] = (byte) (byteLength >>> 8);
			data[byteLengthOffset + 1] = (byte) byteLength;
		}
		if (length + byteLength - offset > data.length) {
			enlarge(byteLength - offset);
		}
		int currentLength = length;
		for (int i = offset; i < charLength; ++i) {
			char charValue = stringValue.charAt(i);
			if (charValue >= 0x0001 && charValue <= 0x007F) {
				data[currentLength++] = (byte) charValue;
			} else if (charValue <= 0x07FF) {
				data[currentLength++] = (byte) (0xC0 | charValue >> 6 & 0x1F);
				data[currentLength++] = (byte) (0x80 | charValue & 0x3F);
			} else {
				data[currentLength++] = (byte) (0xE0 | charValue >> 12 & 0xF);
				data[currentLength++] = (byte) (0x80 | charValue >> 6 & 0x3F);
				data[currentLength++] = (byte) (0x80 | charValue & 0x3F);
			}
		}
		length = currentLength;
		return this;
	}

	/**
	 * Puts an array of bytes into this byte vector. The byte vector is automatically enlarged if
	 * necessary.
	 *
	 * @param byteArrayValue an array of bytes. May be {@literal null} to put {@code byteLength} null
	 *                       bytes into this byte vector.
	 * @param byteOffset     index of the first byte of byteArrayValue that must be copied.
	 * @param byteLength     number of bytes of byteArrayValue that must be copied.
	 * @return this byte vector.
	 */
	public ByteVector putByteArray(
			final byte[] byteArrayValue, final int byteOffset, final int byteLength) {
		if (length + byteLength > data.length) {
			enlarge(byteLength);
		}
		if (byteArrayValue != null) {
			System.arraycopy(byteArrayValue, byteOffset, data, length, byteLength);
		}
		length += byteLength;
		return this;
	}

	/**
	 * Enlarges this byte vector so that it can receive 'size' more bytes.
	 *
	 * @param size number of additional bytes that this byte vector should be able to receive.
	 */
	private void enlarge(final int size) {
		int doubleCapacity = 2 * data.length;
		int minimalCapacity = length + size;
		byte[] newData = new byte[doubleCapacity > minimalCapacity ? doubleCapacity : minimalCapacity];
		System.arraycopy(data, 0, newData, 0, length);
		data = newData;
	}
}
